Democrats attacked Betsy DeVos, President-elect Donald Trump's education nominee, calling her unfit for the job during a contentious confirmation hearing Tuesday evening, while Republicans defended her as a bold reformer who would disrupt the status quo in U.S. education.

DeVos told skeptical senators that she looked forward to working with them to improve the nation's schools. But she sidestepped several issues important to Democrats and their allies, declining to take a position on whether guns belong in schools or to commit to upholding President Barack Obama administration's aggressive approach to handling sexual assault on college campuses, and she called the ideas of Sen. Bernie Sanders', I-Vt., about free college "interesting."

A Michigan billionaire, DeVos has lobbied for decades to expand charter schools and taxpayer-funded vouchers for private and religious schools, but she has no professional experience in public schools, never attended public schools and did not send her own children to public schools. She also has not held public office.

DeVos' inexperience in the realm of public education appeared at times to be a liability. During rapid-fire questioning by Sen. Tim Kaine, D-Va., she seemed to demonstrate a lack of understanding of one of education's major federal civil rights laws, which requires states that take federal funding to provide children with disabilities the services they need to benefit from a public education.

DeVos said states should decide whether schools should be required to meet those special-education requirements.

"So some states might be good to kids with disabilities, and other states might not be so good, and then what, people can just move around the country if they don't like how their kids are being treated?" Kaine said.

When Sen. Maggie Hassan, D-N.H., - who has a son with a disability - challenged DeVos to explain whether she understood that the law was a federal civil rights law, DeVos said she "may have confused it."

DeVos also declined to say whether she thinks that all schools receiving taxpayer funding - public, public charter, or private - should be held accountable to the same performance standards. She also declined to say whether such schools should be required to report suspensions and expulsions, and incidents of bullying and harassment, to the federal government.

Joseph Lieberman, the Democratic nominee for vice president in 2000, introduced DeVos on Tuesday and vouched for her leadership, arguing that her status as an outsider is an asset.

President-elect Donald Trump's transition team acknowledged Friday that Betsy DeVos, Donald Trump's pick for education secretary, omitted a $125,000 political donation from disclosures she submitted to a Senate committee in advance of her confirmation hearing, which is scheduled for Tuesday.

"We...

"She doesn't come from within the education establishment. But honestly, I believe that today that's one of the most important qualifications you could have for this job," the former senator from Connecticut said. "We need a change agent."

DeVos is an unusually polarizing nominee for education secretary; most of her recent predecessors have sailed through the confirmation process, winning Senate approval on voice votes. The strong feelings about DeVos were evident in the line of more than 100 people waiting to enter the Capitol Hill hearing room Tuesday evening, including supportive students in plaid uniforms and bright yellow scarves embroidered with "National School Choice Week," and a large contingent of parents and teens from Detroit who came by bus to oppose Devos's nomination.

GOP senators cheered DeVos' nomination, saying they hope she will champion alternatives to the nation's public schools and scale back the federal footprint in K-12 education.

"Betsy DeVos, in my opinion, is on our children's side," Sen. Lamar Alexander, R-Tenn., chairman of the Health, Education, Labor and Pensions (HELP) Committee, said in his opening remarks Tuesday. "She's devoted her life to helping mainly low-income children have access to better schools."

Alexander dismissed DeVos' critics as out of step with public opinion, arguing that Democrats, including President Obama, have embraced charter schools and that vouchers are patterned on "the most successful social policy this Congress has ever enacted - the GI Bill," which provides tuition assistance for veterans to attend the college of their choice.

"Why is such a great idea for colleges deemed to be such a dangerous idea for K-12 schools?" Alexander said.

He restricted senators to one five-minute round of questions, saying he was adhering to committee precedent and the "golden rule," treating Trump's pick as the committee treated Obama's nominees. Democrats were dismayed, arguing that the committee has never before cut off questions, and that they needed more time to examine DeVos' record.

"I think we're selling our kids short by not being able to ask follow-up questions," said Sen. Al Franken, D-Minn. Franken had asked DeVos for her views on the debate - common in education circles - about whether standardized tests should measure the progress students make during a year, or their grade-level proficiency. He was unimpressed with what he said was her lack of familiarity with that debate.

"I'm surprised you don't know this issue," Franken said.

Teachers unions and civil rights groups have argued that DeVos' support for a free-market approach to education has undermined public schools, which they see as a critical civic institution. DeVos' opponents also point to the fact that she has no record on higher education or protecting children's civil rights, two areas critical to the work of the department she aims to lead.

Asked about her relatives' contributions to anti-LGBT groups, DeVos said she believes in equality: "I believe in the innate value of every single human being and that all students, no matter their age, should be able to attend a school and feel safe and be free of discrimination," she said.

But she declined, under questioning from Sen. Patty Murray (Wash.), the ranking Democrat, to say whether she plans to rein in the Office for Civil Rights, which investigates allegations of discrimination in schools.

Sen. Elizabeth Warren, D-Mass., asked questions about DeVos' qualifications to run the trillion-dollar federal student loan program, with DeVos acknowledging that she has no experience running or managing anything near the size and complexity of the program. DeVos also acknowledged that she had never taken out a federal student loan for herself or her children.

DeVos declined to take a stand on whether guns belong in schools, saying that the decision should be left to local and state officials. She pointed to a rural Wyoming school that is surrounded by a fence to keep bears out: "I would imagine there's probably a gun in the school to protect from potential grizzlies."

Asked by gun control advocate Sen. Chris Murphy, D-Conn., - whose constituents include parents of children who were killed in the mass shooting at Newtown's Sandy Hook Elementary in 2012 - whether she would support Trump if he moves forward with his proposal to ban gun-free school zones, she said she would "support what the president-elect does."

The hearing went forward Tuesday evening over the objections of Democrats, who are concerned that the Office of Government Ethics, which is responsible for vetting presidential nominees for potential conflicts of interest, has not finished its review of DeVos' vast wealth and financial investments.

Alexander has said that the committee won't vote until the ethics office's work is complete. DeVos promised to resolve any conflicts of interest the office identifies. "I will not be conflicted, period," she said. "I commit that to you all."

She said that if confirmed, she will be a "strong advocate for great public schools." But when public schools are "troubled, or unsafe, or not a good fit for a child," she said, parents should have a "right to enroll their child in a high-quality alternative."

"I share President-elect Trump's view that it's time to shift the debate from what the system thinks is best for kids to what moms and dads want, expect and deserve," she said.

On the campaign trail, Trump proposed a new $20 billion grant program to encourage states to expand such efforts, but he offered few details about how that might work, and there is a tension between the incoming administration's interest in expanding vouchers and charter schools and conservatives' interest in leaving decisions about education to states and school districts.

DeVos said Tuesday that she would not coerce states to expand vouchers or charters. But in an exchange with Murray, she also refused to say that she would not work to privatize schools.

Sen. Tim Scott, R-S.C., an advocate for vouchers and charters, called DeVos a champion for low-income children who don't have access to great schools.

"Mrs. DeVos is not opposed to accountability," he said, refuting one of the Democrats' charges against her. "What she is opposed to is leaving children trapped in schools that we know are failing, failing the very students that will have no hope if they do not receive a high-quality education."

The Washington Post's Danielle Douglas-Gabriel and Ed O'Keefe contributed to this report.